# Kuzu MCP Tool Batch Query Improvements
## Summary of Fixes Implemented
### 1. Batch Query Execution Support ✅
**Problem**: `queryResult.getAll is not a function` error when executing multiple CREATE statements
**Solution**:
- Added `processQueryResults()` helper function to handle both single and array results
- Added `executeBatchQuery()` function that:
- First attempts to execute queries as a batch
- If batch fails, automatically splits by semicolon and executes individually
- Provides detailed per-statement results and error tracking
- Maintains partial success (some statements can succeed while others fail)
### 2. Enhanced Error Formatting ✅
**Problem**: JavaScript errors bubble up instead of Kuzu-specific details
**Solution**:
- Created `formatKuzuError()` function that:
- Detects and categorizes specific Kuzu error types
- Extracts meaningful information (e.g., duplicate key values, parse positions)
- Returns structured error objects with error codes and context
- Preserves original error messages for debugging
### 3. Consistent Result Formatting ✅
**Problem**: Empty results returned as `[]` vs objects for other operations
**Solution**:
- Standardized response format: always returns an array with at least one object
- Empty operations return: `[{ result: "Query executed successfully", rowsAffected: 0 }]`
- Batch operations include statement numbers and query text in results
### 4. Improved Primary Key Constraint Handling ✅
**Problem**: Unclear error messages for constraint violations
**Solution**:
- PRIMARY_KEY_VIOLATION errors now include:
- The specific value that caused the violation
- Clear error type classification
- Original error message for reference
### 5. Parser Error Details ✅
**Problem**: Syntax errors lack context
**Solution**:
- PARSER_ERROR responses now include:
- Line and offset position of the error
- Extracted error message without boilerplate
- Error type classification for better handling
## Example Usage
### Successful Batch Execution
```cypher
CREATE (n1:Person {name: "Alice"});
CREATE (n2:Person {name: "Bob"});
CREATE (n3:Person {name: "Charlie"});
```
Returns:
```json
[
{ "statement": 1, "query": "CREATE (n1:Person {name: \"Alice\"})", "result": "Success", "rowsAffected": 0 },
{ "statement": 2, "query": "CREATE (n2:Person {name: \"Bob\"})", "result": "Success", "rowsAffected": 0 },
{ "statement": 3, "query": "CREATE (n3:Person {name: \"Charlie\"})", "result": "Success", "rowsAffected": 0 }
]
```
### Mixed Success/Failure
```cypher
CREATE (n1:Person {name: "Alice"});
CREATE (n2:Person {name: "Alice"}); // Duplicate
CREATE (n3:Person {name: "Bob"});
```
Returns:
```json
[
{ "statement": 1, "query": "CREATE (n1:Person {name: \"Alice\"})", "result": "Success", "rowsAffected": 0 },
{ "statement": 2, "query": "CREATE (n2:Person {name: \"Alice\"})", "error": "Found duplicated primary key value Alice" },
{ "statement": 3, "query": "CREATE (n3:Person {name: \"Bob\"})", "result": "Success", "rowsAffected": 0 }
]
```
### Enhanced Error Response
```json
{
"error": "PRIMARY_KEY_VIOLATION",
"message": "Runtime exception: Found duplicated primary key value Alice, which violates the uniqueness constraint",
"type": "constraint_violation",
"value": "Alice",
"originalError": "Runtime exception: Found duplicated primary key value Alice..."
}
```
## Technical Implementation Details
1. **Batch Processing Logic**:
- Attempts native batch execution first (optimal performance)
- Falls back to sequential execution only on failure
- Preserves transaction semantics where possible
2. **Error Recovery**:
- Partial success is allowed (unlike traditional transactions)
- Each statement's success/failure is tracked independently
- Comprehensive error aggregation for debugging
3. **Type Safety**:
- Fixed TypeScript strict null checks
- Proper array element access with non-null assertions
- Maintained type safety throughout error handling
## Testing Recommendations
1. **Unit Tests**: Test batch execution with various statement combinations
2. **Error Cases**: Verify all constraint violation types produce proper errors
3. **Performance**: Compare batch vs individual execution times
4. **Edge Cases**: Empty queries, malformed syntax, mixed DDL/DML
## Future Enhancements
1. **Composite Primary Key Support**: Requires Kuzu engine updates
2. **Transaction Control**: Add explicit BEGIN/COMMIT support
3. **Query Validation**: Pre-flight syntax checking without execution
4. **Bulk Import**: Optimized CSV/JSON import operations
5. **Connection Pooling**: For concurrent operations
## Migration Notes
- The changes are backward compatible
- Single statement queries work exactly as before
- Error format is enhanced but includes original messages
- No configuration changes required
